Recently, in a new transportation system in which traffic vehicles run on a track or a set route on a road surface or the like, a guide wheel device is provided in a steering mechanism of a guide rail vehicle. In the guide wheel device, guide wheels 53 mounted to front and rear wheel trucks of a vehicle roll with respect to guide rails 52 provided on both the right and left sides of a running track 51 roll in contact with the guide rails 52, to thereby guide the running vehicle along the running track 51 as shown in FIG. 13.
Also, the guide rail 52 includes a main guide rail 52a provided along the running track 51 on both sides thereof, and a branch guide rail 52b provided at a branch position of the running track 51. Therefore, the guide wheel 53 is rotatably provided at each of both right and left end portions of front and rear guide lateral beams (not shown) extending in the vehicle width direction, and includes a main guide wheel 53a and a branch guide wheel 53b rotatably mounted to upper and lower portions of a wheel shaft 54 with the axis being eccentric. The main guide wheel 53a is in contact with the main guide rail 52a, and the branch guide wheel 53b is in contact with the branch guide rail 52b. 
Meanwhile, in the guide wheel device for the guide rail vehicle of a side guide type having the main guide wheel 53a and the branch guide wheel 53b as described above, the wear rate of the main guide wheel 53a is known to be several times higher than that of the branch guide wheel 53b due to a difference in the contact speed and the contact frequency of the main guide wheel 53a and the branch guide wheel 53b with the guide rails 52a and 52b. Since there are limitations on the outer width of the main guide wheel 53a and the outer width of the branch guide wheel 53b from the positional relationship with the branch guide rail 52b, the rotation center of the main guide wheel 53a is provided eccentrically to the axis of the wheel shaft 54. Thus, it is necessary to perform wear adjustment by moving only the main guide wheel 53a to the outer side and thereby displacing the main guide wheel 53a toward the main guide rail 52a without changing the position of the branch guide wheel 53b by use of the eccentricity.
A guide wheel device having a structure in which wear adjustment can be performed on a guide wheel has been conventionally proposed (for example, Patent Literature 1). In the guide wheel device, a lever is bolted to a guide bearing at each wear adjustment position. As shown in FIG. 14, when a guide wheel 62 rotatably supported at both front and rear end portions of a guide arm 61 is worn to generate a gap of a predetermined width or more between the rail of a guide rail and the guide wheel 62, a bolt 66 that fixes to the guide arm 61 a rotation lever 65 fixed to a guide wheel shaft 63 by inhibiting relative rotation with a key 64 is loosened and removed from a threaded hole 67 of the guide arm 61. After that, an operation end portion 65a of the rotation lever 65 is operated.
The guide wheel shaft 63 is thereby rotated based on the rotation operation, and a shaft center C2 of the guide wheel shaft 63 eccentric by a distance e to a shaft center C1 of a support shaft 68 is moved to a changed center around the shaft center C1. Accordingly, the guide wheel 62 is moved to the outer side from the guide arm 61 by a distance corresponding to the displacement amount of the changed center from the shaft center C2 in the right and left direction of the guide arm 61. When an appropriate gap is obtained between the guide rail and the outer peripheral surface of the guide wheel 62 by the movement adjustment, the bolt 66 is screwed into the threaded hole 67 in an intermediate portion and fastened to fix the rotation lever 65, so that the wear adjustment of the guide wheel 62 is completed.
A large-diameter guide shaft portion 68a of the support shaft 68 is arranged at an upper portion of the guide arm 61, a small-diameter mounting shaft portion 68b is inserted into a mounting hole 61a of the guide arm 61, and a branch wheel 69 is supported at a branch wheel shaft portion 68c on the lower end side.